The present invention relates generally apparatus and methods for delivering predetermined formulations and amounts of drugs or other materials to portions of the body with the aid of laser energy. More particularly, the invention relates to apparatus and methods for delivering predetermined formulations and amounts of drugs, medications or other materials to selected portions of tissue in conjunction with surgical and/or percutaneous procedures such as laser-assisted transmyocardial revascularization (TMR) procedures.
In the treatment of heart disease, one method of improving myocardial blood supply is called transmyocardial revascularization (TMR), the creation of channels in the myocardium of the heart. The procedure using needles in a form of surgical xe2x80x9cmyocardial acupuncturexe2x80x9d has been used clinically since the 1960s. Deckelbaum. L. P., Cardiovascular Applications of Laser technology, Lasers in Surgery and Medicine 15:315-341 (1994). It is believed that the technique relieves ischemia by allowing blood to pass from the ventricle through the channels either directly into other vessels communicating with the channels or into myocardial sinusoids which connect to the myocardial microcirculation.
Numerous surgical TMR studies have been performed, including early studies using needles to perform myocardial acupuncture, or boring, to mechanically displace and/or remove tissue. Such studies have involved surgically exposing the heart and sequentially inserting needles to form a number of channels through the epicardium, myocardium, and endocardium to allow blood from the ventricle to perfuse the channels. The early studies using needles showed that the newly created channels were subject to acute thrombosis followed by organization and fibrosis of clots resulting in channel closure. Interest in TMR using needles waned with the knowledge that such channels did not remain open. However, interest in TMR procedures has recurred with the advent of medical lasers used to create TMR channels. Histological evidence of patent, endothelium-lined tracts within laser-created channels shows that the lumen of laser channels can become hemocompatible and remain patent. A thin zone of charring occurs on the periphery of the laser-created channels through the well-known thermal effects of optical radiation on cardiovascular tissue. Additionally, recent histological evidence shows probable new vessel formation adjacent collagen occluded transmyocardial channels, thereby suggesting benefits from TMR with or without the formation of channels which remain patent.
Surgical TMR procedures using laser energy have been described in the prior art. U.S. Pat. No. 4,658,817 issued Apr. 21, 1987 to Hardy teaches a method and apparatus for surgical TMR using a CO2 laser connected to an articulated arm having a handpiece attached thereto. The handpiece emits laser energy from a single aperture and is moved around the surface of the heart to create the desired number of channels. U.S. Pat. No. 5,380,316 issued Jan. 10, 1995 to Aita et al. purports to teach the use of a flexible lasing apparatus which is inserted into the open chest cavity in a surgical procedure. A lens at the distal end of the flexible apparatus is used to focus laser energy, and the apparatus is moved about the surface of the heart to create the desired number of channels.
U.S. Pat. No. 5,389,096 issued Feb. 14, 1995 to Aita et al. purports to teach one method of percutaneous TMR using an elongated flexible lasing apparatus with control lines and a focusing lens structure at the distal tip. The method describes the use of pressure to attempt to stabilize the apparatus against the wall of the heart. None of the cited TMR prior art references suggest delivery of drugs with the TMR apparatus.
In the field of drug delivery, many techniques currently exist for delivering drugs or other materials to the human body. These include, among others, oral administration, injection directly into body tissue such as through an intramuscular injection, transcutaneous injection in which a compound is injected directly into the vasculature of a patient, or topical administration. Although many situations are satisfactorily treated by the general or directed, typically systemic acting administration of a drug, there are a great many treatments which could be facilitated and/or improved by the ability to deliver or administer a drug locally to a selected portion of a patient""s body.
A recent patent, U.S. Pat. No. 5,498,238 issued Mar. 12, 1996 to Shapland et al., discloses a method of simultaneous angioplasty and drug delivery to localized portions of arteries. The patent teaches the use of an expandable balloon end type catheter which can be filled with a drug-containing fluid and which is allowed to permeate through a semi-permeable membrane of the balloon-tip end and thereby be delivered directly to the surface of arteriosclerotic lesions on stenosed arteries. However, the patent does not teach drug delivery in conjunction with any type of laser procedure nor does it contemplate such delivery with the aid of laser energy. Nor does it teach delivery of drugs or other materials directly into tissue located within portions of the body not otherwise directly accessible.
U.S. Pat. No. 5,386,837 to Sterzer discloses an xe2x80x9celectrochemotherapeuticxe2x80x9d technique for treating tumors in which high intensity electromagnetic force fields (including a laser) are applied to the body after chemotherapy has been applied. This is intended to create large, transient pores in individual cells of a superficially-seated tumor lesion located between individually mounted ceramic horn antennae by non-invasively applying a highly directional beam of force-field shock of HF pulsed wave energy into the cells, thus inducing the drug to enter the cells. The patent does not, however, teach apparatus or methods for disposing such drugs or medications into the portion of the body to be treated, but instead relies on the standard approaches to chemotherapy drug delivery. The patent does not anticipate delivery of drugs to selected portions of myocardium in the heart or other internal organs of the body, but rather is directed to augmented chemotherapy to treat breast cancer and prostate cancer or benign prostatic hyperplasia (BPH).
There are a number of important problems that are not addressed by systems of the present art. None of the prior art teaches how to administer drugs from within the tissue to be treated thereby minimizing the amount of drug required, particularly for costly drugs, and also confining the drug or drugs to the particular part of the body or tissue of interest, with more importance in this regard for the administration of toxic drugs. These problems are addressed by the delivery of drugs to the tissue of internal organs, such as the heart, in conjunction with or assisted by laser energy delivery. In particular, with regard to TMR procedures, the use of laser energy combines the latest advances in the development of cardiac medications with the most advanced techniques of TMR in order to enhance and optimize treatment administered to the patient.
In general, this invention is directed to the delivery of drugs in any form in, near or around laser-created openings in structures including organs and other tissue within the human body, and more particularly, this invention is directed toward a system for delivering a drug directly into a channel formed in a target region of the body. The channel is created using essentially any medical laser system, particularly laser systems used in TMR procedures. While TMR procedures have been directed towards revascularization of the heart, it is understood that these principles underlying the devices and methods of use of this invention can be applied to other areas of the body. Therefore, in the context of this specification, the terms target area, target region and target surface include a patient""s heart as well as any other portion of the body to which the practices of this invention can apply, including but not limited to other normal or abnormal tissue, tumors, organs, bones and muscle.
Thus, it is an advantage of the present invention to deliver drugs in all forms to laser-treated tissue.
It is a further advantage to provide an apparatus and method of use for delivering drugs to laser created channels or openings in the human body or on the surface of tissue, for instance surgical or percutaneous TMR sites, which overcome the drug delivery limitations of the prior art.
It is a further advantage of the present invention to deliver medication directly to a localized target region of the body, such as the heart, thereby enabling efficient, cost effective drug treatment and, in the case of highly toxic agents, reduction of damage to healthy tissue.
It is a further advantage of the present invention to provide a system of providing medication to tissue in which the time required for the medication to reach the tissue is reduced, inasmuch as success of such treatment in many situations depends on the medication being able to reach the tissue within a very short period of time.
Another advantage of such a system is the ability to administer a medication directly to target tissue or target areas at preselected times of delivery and rates of delivery.
Another advantage of such a system is the ability to administer saline or flushing solutions directly to target tissue or target areas at preselected times of delivery and rates of delivery.
It is a further advantage of such system to provide means to control not only the rate of delivery but also the composition of the drug or other substance solution according to a control protocol, optionally including capability to modify the administration of such drugs based on vital measurements of patient parameters such as pulse rate, blood pressure or body temperature, etc.
It is yet a further advantage of the present invention to provide a surgical or catheter apparatus which can be positioned securely adjacent a target region in a portion of the vasculature or other organ, including portions of myocardium, to be treated with drugs using laser energy.
A further advantage of the present invention is to provide such apparatus to enable drug delivery in conjunction with, i.e. before, during or after, creation of one or more laser-created openings or channels on or in selected target surfaces within the body quickly and safely.
Additionally, a more specific advantage is to provide drug delivery before, during or after laser creation of TMR channels extending through the myocardiurn, blind channels extending into but not through myocardium, stimulation pockets within myocardium, and other stimulation zones created using laser energy to stimulate angiogenesis.
In a preferred embodiment of the present invention, the apparatus includes a laser delivery means and one or more conduits transmitting drug, the laser delivery means and the one or more drug conduits coming together in a manifold means to direct both, simultaneously or alternatingly, to the target region. The conduits transmitting the drug are separate from the laser delivery means and both are guided into branches of a needle or tube-type manifold. In use, the laser delivery means is extended through a first branch and a common tube of the manifold to the target surface and the laser energy is delivered to form a channel or opening or otherwise act thereon. The drug is transmitted through a second branch and the common tube prior to, simultaneous with or subsequent to formation of the opening or channel. A pointed tube may be mounted on the distal end of the laser delivery means, or the laser delivery means may have a sharpened distal tip, which pierces the target surface prior to applying the laser beam.
Several constructions are contemplated for positioning the target end of the laser delivery means and then transmitting the drug. Construction of the apparatus could include, for example, in a preferred embodiment, a housing which contains one or more syringes whose plungers are controlled manually or automatically. Control of the transmission of drug is exercised by the operator depressing a switch or plunger to dispense drugs into the one or more branches of a needle or other tube-type manifold. The laser delivery means extends through the housing and is extended or retracted by advance means, such as by tuning a thumbwheel in the housing. Adjustable parameters of such hand-held apparatus include switches for activating and controlling delivery of drugs, setting aliquot dosage, repetition rate, etc.
In a preferred method of the present invention, a laser beam from the end of the laser delivery means creates a TMR channel or other opening in the target region. In a second step, which could be performed prior to or simultaneously with the first step, the drug is transmitted through the conduit directly into the TMR channel or other opening. In an optional step, which could either be performed prior to or simultaneously with the first and/or the second steps, the target surface, such as epicardium or endocardium, is pierced with a mechanical piercing means to provide initial access to the target region of tissue, such as myocardium. Delivery of drug ma of course, be accomplished after creation of the channel or opening. Additionally, suction may be provided at the target surface to stabilize the drug delivery and/or the laser apparatus.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.